It is accepted that rotary valves for internal combustion engines are more cost effective, easier to assemble and maintain and, for some proposed designs, even surpass the dependability and durability of poppet valves.
An imperative of a modern high speed engine design is to provide sufficient air for complete combustion under all operating conditions, which will result in cleaner emissions and improved fuel economy. However, this requirement imposes compromises in the design.
These compromises are presently achieved through the use of a large number of components, most of which operate in a reciprocating mode and therefore impose problems due to their inertia. A common design approach is to use multiple smaller and lighter valves. This, however, means a reduction in individual port size and an associated increase in air flow constrictions. Furthermore, the valve inertia, a major limitation in the retraction speed of poppet valves, is addressed only through a reduction of the valve mass. In consequence, a rotary valve system appears to be the only alternative solution for the above problems.
In addition, the conventional, carburetted stratified charge engine design calls for a separate pre-combustion chamber, in which the rich air/fuel mixture is burned (e.g., the Honda CVCC type). This feature, added to the already mentioned multiple valve design and related camshaft and timing mechanisms, results in an extremely complex cylinder head design.
The requirement for a separate pre-combustion chamber may be partially obviated by the use of a diesel-type open chamber direct fuel injection (e.g., the Ford PROCO type). However, there are remaining difficulties which stem principally from free communication between the cylinder chamber and the pre-combustion chamber during the compression stroke. This free communication dilutes the charge in the pre-combustion chamber thereby reducing the power output and the fuel efficiency.
These problems have contributed to the general lack of acceptance of the conventional pre-ignition and stratified engines.
Various apparatuses and arrangements have been suggested to utilise the above mentioned advantages. Some of those were very elaborate, resulting in rather complex and questionable designs.
In most of rotary valve internal combustion engines the air/fuel mixture was fed through a conduit in the rotary valve body, which was used as a communication port between an intake manifold and the cylinder chamber. The combustion products were exhausted through the same or a different passage in said valve body into the exhaust manifold. In same engines the same conduit was used for pre-combustion chamber functions creating problems related to its size, since it had to be large enough not to impose constriction for intake air.
Up to the present time, proposed inventions have not addressed the possibility of using a recess in the rotary valve body for the pre-combustion chamber functions. It is therefore the object of this invention to show that such function is achievable.